Video encoding device, video decoding device, video decoding method, video decoding method, and program

ABSTRACT

A video encoding device includes: pixel bit length increasing means for increasing a pixel bit length of an input image based on pixel bit length increase information; transform means for transforming output data of the pixel bit length increasing means; entropy encoding means for entropy-encoding output data of the transform means; non-compression encoding means for non-compression-encoding input data; multiplexed data selection means for selecting output data of the entropy encoding means or output data of the non-compression encoding means; and multiplexing means for multiplexing the pixel bit length increase information in a bitstream, wherein a pixel bit length of an image corresponding to the output data of the entropy encoding means and a pixel bit length of an image corresponding to the output data of the non-compression encoding means are different from each other.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is Continuation application of U.S. patent applicationSer. No. 13/695,461, filed on Jan. 10, 2013, which is a National Stageof International Application No. PCT/JP2011/003927 filed Jul. 8, 2011,claiming priority based on Japanese Patent Application Nos. 2010-159059,filed Jul. 13, 2010 and 2011-040530 filed Feb. 25, 2011, the contents ofall of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a video encoding device and a videodecoding device that use pixel bit length increase and non-compressionencoding.

BACKGROUND ART

As a video encoding scheme intended for high-efficiency transmission andaccumulation of video information, an encoding scheme of the ISO/IEC14496-10 Advanced Video Coding (AVC) standard is described in Non PatentLiterature (NPL) 2. Moreover, NPL 1 proposes improvement in compressionefficiency of video encoding, by extending (increasing) a pixel bitlength of an input image upon video encoding to enhance operationprecision of intra prediction and motion-compensated prediction(inter-frame prediction).

Patent Literature (PTL) 1 proposes switching between entropy encodingand non-compression encoding (PCM encoding) per predetermined encodedunit, to guarantee a fixed processing time for a video encoding deviceor a video decoding device.

CITATION LIST Patent Literature

-   PTL 1: Japanese Patent Application Laid-Open No. 2004-135251

Non Patent Literature

-   NPL 1: Reiko Noda, Takeshi Chujoh “Improving Video Coding Efficiency    by Pixel Bit-depth Increase”, Forum on Information Technology 2006,    J-009, 2006-   NPL 2: ISO/IEC 14496-10 Advanced Video Coding

SUMMARY OF INVENTION Technical Problem

FIG. 16 is a block diagram showing a video encoding device obtained bysimply combining the technique described in NPL 1 and the techniquedescribed in PTL 1. Hereafter, the video encoding device shown in FIG.16 is referred to as a typical video encoding device.

A structure and an operation of the typical video encoding device thatreceives input of each frame of digitized video and outputs a bitstreamare described below, with reference to FIG. 16.

The video encoding device shown in FIG. 16 includes a pixel bit lengthincreasing unit 101, a transformer/quantizer 102, an entropy encoder103, an inverse transformer/inverse quantizer 104, a buffer 105, apredictor 106, a PCM encoder 107, a PCM decoder 108, a multiplexed dataselector 109, a multiplexer 110, a switch 121, and a switch 122.

The video encoding device shown in FIG. 16 divides each frame intoblocks of 16×16 pixel size called macroblocks (MBs), and encodes each MBsequentially from top left of the frame. In AVC described in NPL 2, eachMB is further divided into blocks of 4×4 pixel size, and each block of4×4 pixel size is encoded.

FIG. 17 is an explanatory diagram showing an example of block divisionin the case where the frame has a spatial resolution of QCIF (QuarterCommon Intermediate Format). The following describes an operation ofeach component by focusing only on pixel values of luminance, forsimplicity's sake.

The pixel bit length increasing unit 101 increases a pixel bit length ofthe block-divided input video, based on pixel bit length increaseinformation set from outside. Let bit_depth_luma be the pixel bit lengthof the input video, and increased_bit_depth_luma be the pixel bit lengthincrease information (increased pixel bit length). The pixel bit lengthincreasing unit 101 shifts each pixel value of the input video to theleft by increased_bit_depth_luma bits. As a result, the output data ofthe pixel bit length increasing unit 101 has a pixel bit length ofbit_depth_luma+increased_bit_depth_luma bits.

A prediction signal supplied from the predictor 106 is subtracted fromthe image increased in pixel bit length which is output from the pixelbit length increasing unit 101, and the resulting image is input to thetransformer/quantizer 102. There are two types of prediction signal,namely, an intra prediction signal and an inter-frame prediction signal.Each of the prediction signals is described below.

The intra prediction signal is a prediction signal created based on animage of a reconstructed picture that has the same display time as acurrent picture and is stored in the buffer 105. Referring to 8.3.1Intra_4×4 prediction process for luma sample, 8.3.2 Intra_8×8 predictionprocess for luma samples, and 8.3.3 Intra_16×16 prediction process forluma samples in NPL 2, intra prediction modes of three block sizes, i.e.Intra_4×4, Intra_8×8, and Intra_16×16, are available for intraprediction.

As can be understood from FIGS. 18(A) and 18(C), Intra_4×4 and Intra_8×8are respectively intra prediction of 4×4 block size and 8×8 block size.Each circle (∘) in FIGS. 18(A) and 18(C) indicates a reference pixelused for intra prediction, i.e. a pixel of the reconstructed picturehaving the same display time as the current picture.

In intra prediction of Intra_4×4, reconstructed peripheral pixels aredirectly set as reference pixels, and used for padding (extrapolation)in nine directions shown in FIG. 18(B) to form the prediction signal. Inintra prediction of Intra_8×8, pixels obtained by smoothing peripheralpixels of the image of the reconstructed picture by low-pass filters (½,¼, ½) shown under the right arrow in FIG. 18(C) are set as referencesignals, and used for extrapolation in the nine directions shown in FIG.18(B) to form the prediction signal.

As shown in FIG. 19(A), Intra_16×16 is intra prediction of 16×16 blocksize. Each circle (∘) in FIG. 19(A) indicates a reference pixel used forintra prediction, i.e. a pixel of the reconstructed picture having thesame display time as the current picture, as in the example shown inFIGS. 18(A),18(B) and 18(C). In intra prediction of Intra_16×16,peripheral pixels of the reconstructed image are directly set asreference pixels, and used for extrapolation in four directions shown inFIG. 19(B) to form the prediction signal.

Hereafter, an MB encoded using the intra prediction signal is referredto as an intra MB, a block size of intra prediction is referred to as anintra prediction mode, and a direction of extrapolation is referred toas an intra prediction direction.

The inter-frame prediction signal is a prediction signal created from animage of a reconstructed picture that has a different display time fromthe current picture and is stored in the buffer 105. Hereafter, an MBencoded using the inter-frame prediction signal is referred to as aninter MB. A block size of the inter MB can be selected from, forexample, 16×16, 16×8, 8×16, 8×8, 8×4, 4×8, and 4×4.

FIG. 20 is an explanatory diagram showing an example of inter-frameprediction using 16×16 block size as an example. A motion vectorMV=(mv_(x), mv_(y)) shown in FIG. 20 is one of prediction parameters ofinter-frame prediction, which indicates the amount of translation of aninter-frame prediction block (inter-frame prediction signal) of areference picture relative to a block to be encoded. In AVC, theprediction parameters of inter-frame prediction include not only aninter-frame prediction direction representing a direction of thereference picture of the inter-frame prediction signal relative to apicture to be encoded of the block to be encoded, but also a referencepicture index for identifying the reference picture used for inter-frameprediction of the block to be encoded. This is because, in AVC, aplurality of reference pictures stored in the buffer 105 can be used forinter-frame prediction.

Inter-frame prediction is described in more detail in 8.4 Interprediction process in NPL 2.

Hereafter, an MB encoded using the inter-frame prediction signal isreferred to as an inter MB, a block size of inter-frame prediction isreferred to as an inter prediction mode, and a direction of inter-frameprediction is referred to as an inter prediction direction.

A picture encoded including only intra MBs is called an I picture. Apicture encoded including not only intra MBs but also inter MBs iscalled a P picture. A picture encoded including inter MBs that use notonly one reference picture but two reference pictures simultaneously forinter-frame prediction is called a B picture. In the B picture,inter-frame prediction in which the direction of the reference pictureof the inter-frame prediction signal relative to the picture to beencoded of the block to be encoded is to the past is called forwardprediction, inter-frame prediction in which the direction of thereference picture of the inter-frame prediction signal relative to thepicture to be encoded of the block to be encoded is to the future iscalled backward prediction, and inter-frame prediction involving boththe past and the future is called bidirectional prediction.

The transformer/quantizer 102 frequency-transforms the image increasedin pixel bit length from which the prediction signal has been subtracted(prediction error image).

The transformer/quantizer 102 further quantizes thefrequency-transformed prediction error image (frequency transformcoefficient), with a quantization step width Qs according to theincreased pixel bit length increased_bit_depth_luma of the pixel bitlength increasing unit 101. Let Qs_(luma) be a normal quantization stepwidth. Then, Qs=Qs_(luma)*2^(increased) ^(_) ^(bit) ^(_) ^(depth) ^(_)^(luma), as an example. Hereafter, the quantized frequency transformcoefficient is referred to as a transform quantization value.

The entropy encoder 103 entropy-encodes prediction parameters and thetransform quantization value. The prediction parameters are informationrelated to MB prediction, such as intra MB/inter MB, intra predictionmode, intra prediction direction, inter MB block size, and motion vectormentioned above.

The inverse transformer/inverse quantizer 104 inverse-quantizes thetransform quantization value, with the quantization step width accordingto the increased pixel bit length increased_bit_depth_luma of the pixelbit length increasing unit 101. The inverse transformer/inversequantizer 104 further inverse-frequency-transforms the frequencytransform coefficient obtained by the inverse quantization. Theprediction signal is added to the reconstructed prediction error imageobtained by the inverse frequency transform, and the resulting image issupplied to the switch 122.

The multiplexed data selector 109 monitors the amount of input data perpredetermined encoded unit (e.g. macroblock) to the entropy encoder 103.In the case where the entropy encoder 103 is capable of entropy-encodingthe input data within a processing time corresponding to thepredetermined encoded unit, the multiplexed data selector 109 controlsthe switch 121 to select the output data of the entropy encoder 103. Asa result, the output data of the entropy encoder 103 is supplied to themultiplexer 110 via the switch 121. The multiplexed data selector 109further controls the switch 122 to select the output data of the inversetransformer/inverse quantizer 104. As a result, the output data of theinverse transformer/inverse quantizer 104 is supplied to the buffer 105via the switch 122.

In the case where the entropy encoder 103 is not capable ofentropy-encoding the input data within the processing time, themultiplexed data selector 109 controls the switch 121 to select theoutput data of the PCM encoder 107 obtained by PCM-encoding the outputdata of the pixel bit length increasing unit 101. As a result, theoutput data of the PCM encoder 107 is supplied to the multiplexer 110via the switch 121. The multiplexed data selector 109 further controlsthe switch 122 to select the output data of the PCM decoder 108 obtainedby PCM-decoding the output data of the PCM encoder 107. As a result, theoutput data of the PCM decoder 108 is supplied to the buffer 105 via theswitch 122.

The buffer 105 stores the reconstructed image supplied via the switch122. The reconstructed image per frame is referred to as a reconstructedpicture.

The multiplexer 110 multiplexes the pixel bit length increaseinformation with the output data of the entropy encoder 103 and theoutput data of the PCM encoder 107, and outputs the multiplexing result.

Based on the operation described above, the typical video encodingdevice creates the bitstream.

In the case of using the typical technique described above, it ispossible to both enhance operation precision of intra prediction orinter-frame prediction by pixel bit length extension and guarantee afixed processing time for a video encoding device or a video decodingdevice.

However, in the typical technique described above, the image increasedin pixel bit length is PCM-encoded, which causes a problem that outputdata of PCM encoding increases by the pixel bit length increase amountdespite a lack of PSNR (Peak Signal to Noise Ratio) improvement. Forexample, in the case where bit_depth_luma is 8 bits andincreased_bit_depth_luma is 8 bits, the output data of PCM encoding is16 bits, which is twice as large as the 8-bit input image.

In view of this, the present invention has an object of suppressingincrease of output data of PCM encoding, in video encoding based onpixel bit length increase and PCM encoding.

Solution to Problem

A video encoding device according to the present invention includes:pixel bit length increasing means for increasing a pixel bit length ofan input image based on pixel bit length increase information; transformmeans for transforming output data of the pixel bit length increasingmeans; entropy encoding means for entropy-encoding output data of thetransform means; non-compression encoding means fornon-compression-encoding input data; multiplexed data selection meansfor selecting output data of the entropy encoding means or output dataof the non-compression encoding means; and multiplexing means formultiplexing the pixel bit length increase information in a bitstream,wherein a pixel bit length of an image corresponding to the output dataof the entropy encoding means and a pixel bit length of an imagecorresponding to the output data of the non-compression encoding meansare different from each other.

A video decoding device according to the present invention includes:de-multiplexing means for de-multiplexing a bitstream including at leastpixel bit length increase information; entropy decoding means forentropy-decoding transformed data of an image included in the bitstream;inverse transform means for inverse-transforming the entropy-decodedtransformed data of the image; non-compression decoding means fornon-compression-decoding non-compression-encoded data of an imageincluded in the bitstream; and decoding control means for controllingthe entropy decoding means and the non-compression decoding means,wherein a pixel bit length of an image corresponding to input data ofthe entropy decoding means and a pixel bit length of an imagecorresponding to input data of the non-compression decoding means aredifferent from each other.

A video encoding method according to the present invention includes:transforming data obtained by increasing a pixel bit length of an inputimage based on pixel bit length increase information; entropy-encodingthe transformed data; non-compression-encoding input data; selecting theentropy-encoded data or the non-compression-encoded data; andmultiplexing the pixel bit length increase information in a bitstream,wherein a pixel bit length of an image corresponding to theentropy-encoded data and a pixel bit length of an image corresponding tothe non-compression-encoded data are different from each other.

A video decoding method according to the present invention includes:de-multiplexing a bitstream including at least pixel bit length increaseinformation; entropy-decoding transformed data of an image included inthe bitstream; inverse-transforming the entropy-decoded transformed dataof the image; and non-compression-decoding non-compression-encoded dataof an image included in the bitstream, wherein a pixel bit length of animage corresponding to the transformed data of the image included in thebitstream and a pixel bit length of an image corresponding to thenon-compression-encoded data of the image included in the bitstream aredifferent from each other.

A video encoding program according to the present invention causes acomputer to execute: a process of transforming data obtained byincreasing a pixel bit length of an input image based on pixel bitlength increase information; a process of entropy-encoding thetransformed data; a process of non-compression-encoding input data; aprocess of selecting the entropy-encoded data or thenon-compression-encoded data; and a process of multiplexing the pixelbit length increase information in a bitstream, wherein a pixel bitlength of an image corresponding to the entropy-encoded data and a pixelbit length of an image corresponding to the non-compression-encoded dataare different from each other.

A video decoding program according to the present invention causes acomputer to execute: a process of de-multiplexing a bitstream includingat least pixel bit length increase information; a process ofentropy-decoding transformed data of an image included in the bitstream;a process of inverse-transforming the entropy-decoded transformed dataof the image; and a process of non-compression-decodingnon-compression-encoded data of an image included in the bitstream,wherein a pixel bit length of an image corresponding to the transformeddata of the image included in the bitstream and a pixel bit length of animage corresponding to the non-compression-encoded data of the imageincluded in the bitstream are different from each other.

Advantageous Effects of Invention

According to the present invention, it is possible to suppress increaseof output data of PCM encoding, in video encoding based on pixel bitlength increase and PCM encoding.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a video encoding device in ExemplaryEmbodiment 1.

FIG. 2 is an explanatory diagram showing pixel bit length increaseinformation in sequence parameters.

FIG. 3 is a flowchart showing processing of the video encoding device inExemplary Embodiment 1.

FIG. 4 is a block diagram of a video decoding device in ExemplaryEmbodiment 2.

FIG. 5 is a flowchart showing processing of the video decoding device inExemplary Embodiment 2.

FIG. 6 is a block diagram of a video encoding device in anotherexemplary embodiment.

FIG. 7 is an explanatory diagram showing another example of pixel bitlength increase information in sequence parameters.

FIG. 8 is an explanatory diagram showing yet another example of pixelbit length increase information in sequence parameters.

FIG. 9 is an explanatory diagram showing yet another example of pixelbit length increase information in sequence parameters.

FIG. 10 is a block diagram showing a structural example of aninformation processing system capable of realizing functions of a videoencoding device and a video decoding device according to the presentinvention.

FIG. 11 is a block diagram showing a main part of a video encodingdevice according to the present invention.

FIG. 12 is a block diagram showing a main part of another video encodingdevice according to the present invention.

FIG. 13 is a block diagram showing a main part of yet another videoencoding device according to the present invention.

FIG. 14 is a block diagram showing a main part of a video decodingdevice according to the present invention.

FIG. 15 is a block diagram showing a main part of another video decodingdevice according to the present invention.

FIG. 16 is a block diagram showing a typical video encoding device.

FIG. 17 is an explanatory diagram showing an example of block division.

FIGS. 18(A),18(B) and 18(C) are explanatory diagrams showing predictiontypes.

FIGS. 19(A) and 19(B) are an explanatory diagrams showing predictiontypes.

FIG. 20 is an explanatory diagram showing an example of inter-frameprediction using 16×16 block size as an example.

DESCRIPTION OF EMBODIMENTS Exemplary Embodiment 1

A video encoding device in this exemplary embodiment includes: means formaking a pixel bit length of an image corresponding to output data ofentropy encoding and a pixel bit length of an image corresponding tooutput data of PCM encoding different from each other; means forincreasing a pixel bit length of a decoded image of PCM decoding basedon pixel bit length increase information; and means for multiplexing thepixel bit length increase information in a bitstream.

As shown in FIG. 1, the video encoding device in this exemplaryembodiment includes a pixel bit length increasing unit 111 forincreasing a pixel bit length of a decoded image of the PCM decoder 108based on pixel bit length increase information, in addition to the pixelbit length increasing unit 101, the transformer/quantizer 102, theentropy encoder 103, the inverse transformer/inverse quantizer 104, thebuffer 105, the predictor 106, the PCM encoder 107, the PCM decoder 108,the multiplexed data selector 109, the multiplexer 110, the switch 121,and the switch 122 included in the typical video encoding device shownin FIG. 16.

When comparing FIGS. 1 and 16, it can be understood that the videoencoding device in this exemplary embodiment supplies an input imagebefore pixel bit length increase to the PCM encoder 107, in order tomake a pixel bit length of an image corresponding to output data ofentropy encoding and a pixel bit length of an image corresponding tooutput data of PCM encoding different from each other. The imagecorresponding to the output data of entropy encoding is an image ofinput video increased in pixel bit length which is supplied to thetransformer/quantizer 102, and a reconstructed image of the image of theinput video increased in pixel bit length which is supplied from theinverse transformer/inverse quantizer 104. The image corresponding tothe output data of PCM encoding is an image of input video not increasedin pixel bit length which is supplied to the PCM encoder 107, and aPCM-decoded image of the input video not increased in pixel bit lengthwhich is supplied from the PCM decoder 108.

The pixel bit length increasing unit 101 increases a pixel bit length ofblock-divided input video, based on pixel bit length increaseinformation set from outside.

Let bit_depth_luma be a pixel bit length of luminance of the inputvideo, and increased_bit_depth_luma be pixel bit length increaseinformation of luminance (increased pixel bit length). The pixel bitlength increasing unit 101 shifts each pixel value of luminance of theinput video to the left by increased_bit_depth_luma bits. As a result,the output data of the pixel bit length increasing unit 101 has a pixelbit length of bit_depth_luma+increased_bit_depth_luma bits. Likewise,for color difference (Cb and Cr components), let bit_depth_chroma be apixel bit length of color difference of the input video, andincreased_bit_depth_chroma be pixel bit length increase information ofcolor difference. The pixel bit length increasing unit 101 shifts eachpixel value of color difference of the input video to the left byincreased_bit_depth_luma bits.

A prediction signal supplied from the predictor 106 is subtracted fromthe image increased in pixel bit length which is output from the pixelbit length increasing unit 101, and the resulting image is input to thetransformer/quantizer 102. The transformer/quantizer 102frequency-transforms the image increased in pixel bit length from whichthe prediction signal has been subtracted (prediction error image).

The transformer/quantizer 102 further quantizes thefrequency-transformed prediction error image (frequency transformcoefficient), with a quantization step width Qs according to theincreased pixel bit lengths increased_bit_depth_luma andincreased_bit_depth_chroma of the pixel bit length increasing unit 101.Let Qs_(luma) be a normal quantization step width of luminance. Then,Qs=Qs_(luma)*2^(increased) ^(_) ^(bit) ^(_) ^(depth) ^(_) ^(luma), as anexample. Hereafter, the quantized frequency transform coefficient isreferred to as a transform quantization value.

The entropy encoder 103 entropy-encodes prediction parameters suppliedfrom the predictor 106 and the transform quantization value suppliedfrom the transformer/quantizer 102. The prediction parameters areinformation related to macroblock prediction, such as intra MB/inter MB,intra prediction mode, intra prediction direction, inter MB block size,and motion vector.

The inverse transformer/inverse quantizer 104 inverse-quantizes thetransform quantization value, with the quantization step width accordingto the increased pixel bit lengths increased_bit_depth_luma andincreased_bit_depth_chroma of the pixel bit length increasing unit 101.The inverse transformer/inverse quantizer 104 furtherinverse-frequency-transforms the frequency transform coefficientobtained by the inverse quantization. The prediction signal is added tothe reconstructed prediction error image obtained by the inversefrequency transform, and the resulting image is supplied to the switch122.

The PCM encoder 107 PCM-encodes the input image before the increase ofthe pixel bit length. Output data pcm_sample_luma[i] of luminance of thePCM encoder 107 has the pixel bit length bit_depth_luma of luminance ofthe input video. Here, i (0≦i≦255) is an index in raster scan orderwithin the macroblock. Likewise, output data pcm_sample_chroma[i] (i:0≦i≦127) of color difference of the PCM encoder 107 has the pixel bitlength bit_depth_chroma of color difference of the input video.

The PCM decoder 108 PCM-decodes pcm_sample_luma[i] andpcm_sample_chroma[i]. Hereafter, PCM decoding is also referred to as PCMdata reading.

The pixel bit length increasing unit 111 shifts PCM-data-readpcm_sample_luma[i] to the left by increased_bit_depth_luma bits. As aresult, a reconstructed image obtained via the PCM decoder 108 hasbit_depth_luma+increased_bit_depth_luma bits, and is supplied to theswitch 122. Likewise, PCM-data-read pcm_sample_chroma[i] is shifted tothe left by increased_bit_depth_chroma bits, and supplied to the switch122.

The multiplexed data selector 109 monitors the amount of input data perpredetermined encoded unit (e.g. macroblock) to the entropy encoder 103.In the case where the entropy encoder 103 is capable of entropy-encodingthe input data within a processing time corresponding to thepredetermined encoded unit, the multiplexed data selector 109 controlsthe switch 121 to select the output data of the entropy encoder 103. Asa result, the output data of the entropy encoder 103 is supplied to themultiplexer 110 via the switch 121. The multiplexed data selector 109further controls the switch 122 to select the output data of the inversetransformer/inverse quantizer 104. As a result, the output data of theinverse transformer/inverse quantizer 104 is supplied to the buffer 105via the switch 122.

In the case where the entropy encoder 103 is not capable ofentropy-encoding the input data within the processing time, themultiplexed data selector 109 first causes the entropy encoder 103 toencode and output information indicating that the macroblock is an intraMB of PCM. In detail, when complying with 7.3.5 Macroblock layer syntaxin NPL 2, mb_type is entropy-encoded and output as I_PCM.

Following this, the output bit of the entropy encoder 103 isbyte-aligned. In detail, when complying with 7.3.5 Macroblock layersyntax in NPL 2, the entropy encoder 103 supplies a predetermined numberof pcm_alignment_zero_bit to the multiplexer 110. Moreover, the entropyencoder 103 initializes an encoding engine, for subsequent encoding.

An example of encoding engine initialization is described in 9.3.4.1Initialization process for the arithmetic encoding engine (informative)in NPL 2.

The multiplexed data selector 109 further controls the switch 121 toselect the output data of the PCM encoder 107. As a result, the outputdata of the PCM encoder 107 is supplied to the multiplexer 110 via theswitch 121.

Lastly, the multiplexed data selector 109 controls the switch 122 toselect the output data of the pixel bit length increasing unit 111. As aresult, the output data of the pixel bit length increasing unit 111 issupplied to the buffer 105 via the switch 122. Here, the pixel bitlength increasing unit 111 increases the number of bits by shifting, tothe left by increased_bit_depth_luma bits, the output datapcm_sample_luma[i] of the PCM decoder 108 obtained by reading the outputdata pcm_sample_luma[i] of the PCM encoder 107. Likewise, the pixel bitlength increasing unit 111 increases the number of bits by shifting, tothe left by increased_bit_depth_chroma bits, the output datapcm_sample_chroma[i] of the PCM decoder 108 obtained by reading theoutput data pcm_sample_chroma[i] of the PCM encoder 107.

The multiplexer 110 multiplexes the pixel bit length increaseinformation with the output data of the entropy encoder 103 and theoutput data of the PCM encoder 107, and outputs the multiplexing result.When complying with Specification of syntax functions, categories, anddescriptors in NPL 2, the pixel bit length increase information(increased_bit_depth_luma and increased_bit_depth_chroma) may bemultiplexed following bit_depth_luma_minus8 and bit_depth_chroma_minus8of sequence parameters, as in the list shown in FIG. 2. Here,bit_depth_luma_minus8 is a value obtained by subtracting 8 from thepixel bit length bit_depth_luma of luminance of the input video,bit_depth_chroma_minus8 is a value obtained by subtracting 8 from thepixel bit length bit_depth_chroma of color difference of the inputvideo, increased_bit_depth_luma is the increased pixel bit length ofluminance, and increased_bit_depth_chroma is the increased pixel bitlength of color difference.

The expressions (“C” and “Descriptor”) in the list shown in FIG. 2 are,for example, in compliance with 7.2 Specification of syntax functions,categories, and descriptors in NPL 2.

Based on the operation described above, the video encoding device inthis exemplary embodiment creates the bitstream.

Operations of the entropy encoder 103, the PCM encoder 107, the PCMdecoder 108, and the pixel bit length increasing unit 111 in the case ofnot being capable of entropy-encoding within the processing time, whichare features of the present invention, are described below withreference to the flowchart in FIG. 3.

As shown in FIG. 3, in step S101, the entropy encoder 103entropy-encodes mb_type as I_PCM and supplies it to the multiplexer 110,in order to guarantee a fixed processing time for a video encodingdevice or a video decoding device.

In step S102, the entropy encoder 103 supplies pcm_alignment_zero_bit tothe multiplexer 110, to byte-align the output bit.

In step S103, the entropy encoder 103 initializes the encoding enginefor subsequent entropy encoding.

In step S104, the PCM encoder 107 PCM-encodes the input image before theincrease of the pixel bit length and supplies it to the multiplexer 110,so as not to increase output data of PCM encoding.

In step S105, the PCM decoder 108 PCM-decodes (PCM-data-reads) the PCMencoding result pcm_sample_luma[i] and pcm_sample_chroma[i].

In step S106, the pixel bit length increasing unit 111 shiftspcm_sample_luma[i] and pcm_sample_chroma[i] PCM-data-read by the PCMdecoder 108 to the left respectively by increased_bit_depth_luma bitsand increased_bit_depth_chroma bits, in order to enhance operationprecision of subsequent intra prediction and inter-frame prediction.

Thus, in the case of not being capable of entropy-encoding within theprocessing time corresponding to the predetermined encoded unit, theentropy encoder 103 and the PCM encoder 107 operate as described above.

In the video encoding device in this exemplary embodiment, the inputimage before the increase of the pixel bit length is supplied to the PCMencoder 107, in order to make the pixel bit length of the imagecorresponding to the output data of entropy encoding and the pixel bitlength of the image corresponding to the output data of PCM encodingdifferent from each other. Such a structure enables suppression ofincrease of output data of PCM encoding, in video encoding based onpixel bit length increase and non-compression encoding.

Moreover, the video encoding device in this exemplary embodimentincludes the pixel bit length increasing unit 111 for increasing thepixel bit length of the decoded image of PCM decoding based on the pixelbit length increase information. The pixel bit length increasing unit111 can suppress reduction of operation precision of intra predictionand inter-frame prediction caused by making the pixel bit lengthsdifferent from each other.

Furthermore, in the video encoding device in this exemplary embodiment,the multiplexer 110 multiplexes the pixel bit length increaseinformation in the bitstream so that the pixel bit length of the decodedimage of PCM decoding is equally increased in video decoding. Such astructure contributes to enhanced interoperability of the video encodingdevice and the video decoding device. That is, the video encoding deviceand the video decoding device co-operate with each other, with it beingpossible to suppress increase of PCM encoding in the system and alsosuppress reduction of operation precision of intra prediction andinter-frame prediction.

Exemplary Embodiment 2

A video decoding device in this exemplary embodiment decodes a bitstreamin which a pixel bit length of an image corresponding to input data ofentropy decoding means and a pixel bit length of an image correspondingto input data of PCM decoding means are different from each other. Theimage corresponding to the input data of the entropy decoding means is areconstructed image of an image of input video increased in pixel bitlength which is supplied from an inverse transformer/inverse quantizer206 described later. The image corresponding to the input data of thePCM decoding means is a PCM-decoded image of input video not increasedin pixel bit length which is supplied from a PCM decoder 203 describedlater.

As shown in FIG. 4, the video decoding device in this exemplaryembodiment includes a de-multiplexer 201, a decoding controller 202, thePCM decoder 203, an entropy decoder 204, a pixel bit length increasingunit 205, the inverse transformer/inverse quantizer 206, a predictor207, a buffer 208, a pixel bit length decreasing unit 209, a switch 221,and a switch 222.

The de-multiplexer 201 de-multiplexes an input bitstream, to extractpixel bit length increase information and an entropy-encoded orPCM-encoded video bitstream. When complying with Specification of syntaxfunctions, categories, and descriptors in NPL 2, the pixel bit lengthincrease information (increased_bit_depth_luma andincreased_bit_depth_chroma) following bit_depth_luma_minus8 andbit_depth_chroma_minus8 of the sequence parameters as in the list shownin FIG. 2 is extracted.

The entropy decoder 204 entropy-decodes the video bitstream. In the casewhere mb_type of a macroblock is not I_PCM (PCM encoding), the entropydecoder 204 entropy-decodes prediction parameters and a transformquantization value of the macroblock, and supplies them to the inversetransformer/inverse quantizer 206 and the predictor 207.

The inverse transformer/inverse quantizer 206 inverse-quantizes thetransform quantization value of luminance and color difference, with aquantization step width according to the pixel bit length increaseinformation increased_bit_depth_luma and increased_bit_depth_chromaextracted by the de-multiplexing. The inverse transformer/inversequantizer 206 further inverse-frequency-transforms the frequencytransform coefficient obtained by the inverse quantization.

The predictor 207 creates a prediction signal using an image of areconstructed picture stored in the buffer 208, based on theentropy-decoded prediction parameters.

The prediction signal supplied from the predictor 207 is added to thereconstructed prediction error image obtained by the inverse frequencytransform by the inverse transformer/inverse quantizer 206, and theresulting image is supplied to the switch 222.

The decoding controller 202 changes the switch 222 so that thereconstructed prediction error image to which the prediction signal hasbeen added is supplied to the buffer 208 as the reconstructed image.

In the case where mb_type of the macroblock is PCM encoding, thedecoding controller 202 causes the de-multiplexer 201 to byte-align thevideo bitstream which is in the middle of entropy decoding. Whencomplying with 7.3.5 Macroblock layer syntax in NPL 2, the decodingcontroller 202 causes the de-multiplexer 201 to readpcm_alignment_zero_bit until the video bitstream is byte-aligned.

The decoding controller 202 then causes the entropy decoder 204 toinitialize a decoding engine. An example of decoding engineinitialization is described in 9.3.1.2 Initialization process for thearithmetic decoding engine in NPL 2.

Following this, the decoding controller 202 changes the switch 221 sothat the byte-aligned video bitstream is supplied to the PCM decoder203.

The PCM decoder 203 PCM-decodes (PCM-data-reads) PCM-encoded luminancedata pcm_sample_luma[i] and color difference data pcm_sample_chroma[i]from the byte-aligned video bitstream.

The pixel bit length increasing unit 205 shifts PCM-data-readpcm_sample_luma[i] and pcm_sample_chroma[i] to the left, respectivelyaccording to the pixel bit length increase informationincreased_bit_depth_luma and increased_bit_depth_chroma extracted by thede-multiplexing. When complying with the description of 8.3.5 Sampleconstruction process for I_PCM macroblocks in NPL 2, a PCM-decodedluminance image S′L and a PCM-decoded color difference image S′Cb andS′Cr are computed according to Equation (8-154′) and Equation (8-155′)below.

$\begin{matrix}{ {{{for}\;( {{i = 0};{i < 256};{i++}} )}{S^{\prime}{L\lbrack {{{xP} + ( {i\mspace{14mu}\%\mspace{14mu} 16} )},{{yP} + {{dy}*( {i/16} )}}} )}}} \rbrack = ( {{{pcm\_ sample}{{\_ luma}\lbrack i\rbrack}} ⪡ {{increased\_ bit}{\_ depth}{\_ luma}}} )} & ( {8\text{-}154^{\prime}} ) \\{{{for}\;( {{i = 0};{i < {{MbWidthC}*{MbHeightC}}};{i++}} )}\{ {{S^{\prime}{{Cb}\lbrack {{( {{xP}/{SubWidthC}} ) + ( {i\mspace{14mu}\%\mspace{14mu}{MbWidthC}} )},{( {( {{yP} + {SubHeightC} - 1} )/{SubHeightC}} ) + {{dy}*( {i/{MbWidthC}} )}}} \rbrack}} = {{( {{{pcm\_ sample}{{\_ chroma}\lbrack i\rbrack}} ⪡ {{increased\_ bit}{\_ depth}{\_ chroma}}} )S^{\prime}{{Cr}\lbrack {{( {{xP}/{SubWidthC}} ) + ( {i\mspace{14mu}\%\mspace{14mu}{MbWidthC}} )},{( {( {{yP} + {SubHeightC} - 1} )/{SubHeightC}} ) + {{dy}*( {i/{MbWidthC}} )}}} \rbrack}} = ( {{{pcm\_ sample}{{\_ chroma}\lbrack {i + {{MbWidthC}*{MbHeightC}}} \rbrack}} ⪡ {{increased\_ bit}{\_ depth}{\_ chroma}}} )}} \}} & ( {8\text{-}155^{\prime}} )\end{matrix}$

The decoding controller 202 changes the switch 222 so that thePCM-decoded image increased in pixel bit length is supplied to thebuffer 208 as the reconstructed image. The decoding controller 202changes the switch 221 so that the output data of the de-multiplexer 201is supplied to the entropy decoder 204, for decoding of a nextmacroblock.

The pixel bit length decreasing unit 209 decreases the pixel bit lengthof the reconstructed picture stored in the buffer 208 according to thepixel bit length increase information increased_bit_depth_luma andincreased_bit_depth_chroma extracted by the de-multiplexing, and outputsthe result.

Based on the operation described above, the video decoding device inthis exemplary embodiment creates the decoded image.

Operations of the decoding controller 202, the entropy decoder 204, thePCM decoder 203, and the pixel bit length increasing unit 205 in thecase where mb_type of the macroblock is PCM encoding, which are featuresof the present invention, are described below with reference to theflowchart in FIG. 5.

In step S201, the de-multiplexer 201 reads pcm_alignment_zero_bit so asto byte-align the video bitstream which is in the middle of entropydecoding.

In step S202, the entropy decoder 204 initializes the decoding enginefor subsequent entropy decoding.

In step S203, the PCM decoder 203 PCM-decodes (PCM-data-reads) the PCMencoding result pcm_sample_luma[i] and pcm_sample_chroma[i].

In step S204, the pixel bit length increasing unit 205 shiftsPCM-data-read pcm_sample_luma[i] and pcm_sample_chroma[i] to the leftrespectively by increased_bit_depth_luma bits andincreased_bit_depth_chroma bits, in order to enhance operation precisionof subsequent intra prediction and inter-frame prediction.

Thus, in the case where mb_type of the macroblock is PCM encoding, thedecoding controller 202, the entropy decoder 204, the PCM decoder 203,and the pixel bit length increasing unit 205 operate as described above.

The video decoding device in this exemplary embodiment includes thepixel bit length increasing unit 205 for increasing the pixel bit lengthof the decoded image of PCM decoding based on the pixel bit lengthincrease information extracted by the de-multiplexing. The pixel bitlength increasing unit 205 can suppress reduction of operation precisionof intra prediction and inter-frame prediction caused by making thepixel bit lengths of the images corresponding to the inputs of theentropy decoding means and the PCM decoding means different from eachother. Moreover, the reconstructed image same as in video decoding canbe obtained, which contributes to enhanced interoperability of the videoencoding device and the video decoding device. That is, the videoencoding device and the video decoding device co-operate with eachother, with it being possible to suppress increase of PCM encoding inthe system and also suppress reduction of operation precision of intraprediction and inter-frame prediction.

The video encoding device in Exemplary Embodiment 1 shown in FIG. 1 is avideo encoding device that supplies the input image before the increaseof the pixel bit length to the PCM encoder 107, in order to make thepixel bit length of the image corresponding to the output data ofentropy encoding and the pixel bit length of the image corresponding tothe output data of PCM encoding different from each other.

FIG. 6 is a block diagram showing a video encoding device of anotherstructure for achieving the same advantageous effects as the videoencoding device shown in FIG. 1.

When compared with the video encoding device shown in FIG. 1, the videoencoding device shown in FIG. 6 additionally includes a pixel bit lengthdecreasing unit 112. That is, the video encoding device shown in FIG. 6has a structure in which the pixel bit length decreasing unit 112 thatreceives the image increased in pixel bit length supplies, to the PCMencoder 107, the image decreased in pixel bit length based on the pixelbit length increase information. As in Exemplary Embodiment 1, the videoencoding device shown in FIG. 6 can suppress increase of output data ofPCM encoding, and also suppress reduction of operation precision ofintra prediction and inter-frame prediction caused by making the pixelbit lengths different from each other.

In each of the exemplary embodiments described above, the pixel of thereconstructed picture is a pixel increased in pixel bit length. For sizereduction of the buffer for storing the reconstructed picture, however,an exemplary embodiment in which the above-mentioned pixel bit lengthincreasing unit and pixel bit length decreasing unit are used forinput/output of the buffer is also conceivable. In such an exemplaryembodiment, too, the suppression of increase of output data of PCMencoding and the suppression of reduction of operation precision ofintra prediction caused by making the pixel bit lengths different fromeach other can both be achieved according to the present invention.

In each of the exemplary embodiments described above, the PCM decoderand the pixel bit length increasing unit are independent functionalblocks. As can be easily understood from Equation (8-154′) and Equation(8-155′), however, the PCM decoder and the pixel bit length increasingunit may be integrated as one functional block.

In each of the exemplary embodiments described above, the video encodingdevice multiplexes increased_bit_depth_luma andincreased_bit_depth_chroma in the bitstream followingbit_depth_luma_minus8 and bit_depth_chroma_minus8, in order toexplicitly signal the pixel bit length increase information to the videodecoding device (see FIG. 2). Alternatively, the video encoding devicemay multiplex, as the pixel bit length increase information, pixel bitlength information after the increase of the pixel bit length in thebitstream, in order to implicitly signal the pixel bit length increaseinformation to the video decoding device (it is assumed here that theoriginal pixel bit length of the input video is, for example, 8 bits inthe video encoding device and the video decoding device).

In this case, the video encoding device multiplexes pixel bit lengthincrease information (internal_bit_depth_luma_minus8 andinternal_bit_depth_chroma_minus8) shown in FIG. 7 in the sequenceparameters, instead of bit_depth_luma_minus8 and bit_depth_chroma_minus8of the sequence parameters. Here, internal_bit_depth_luma_minus8 is thevalue of increased_bit_depth_luma, and internal_bit_depth_chroma_minus8is the value of increased_bit_depth_chroma.

In the case of multiplexing the pixel bit length increase informationshown in FIG. 7 in the sequence parameters, the PCM encoder 107PCM-encodes the input image before the increase of the pixel bit length.That is, the PCM encoder 107 PCM-encodes 8-bit pcm_sample_luma[i] andpcm_sample_chroma[i]. The PCM decoder 108 PCM-decodes 8-bitpcm_sample_luma[i] and pcm_sample_chroma[i]. The pixel bit lengthincreasing unit 111 shifts PCM-decoded pcm_sample_luma[i] andpcm_sample_chroma[i] to the left respectively byincreased_bit_depth_luma bits and increased_bit_depth_chroma bits.

A video decoding device corresponding to the case of multiplexing thepixel bit length increase information shown in FIG. 7 in the sequenceparameters de-multiplexes the pixel bit length increase information(internal_bit_depth_luma_minus8 and internal_bit_depth_chroma_minus8)from the sequence parameters, and computes increased_bit_depth_luma andincreased_bit_depth_chroma as follows.

increased_bit_depth_luma=internal_bit_depth_luma_minus8

increased_bit_depth_chroma=internal_bit_depth_chroma_minus8

By the above-mentioned computation, the video decoding device cande-multiplex the pixel bit length increase information implicitlysignaled by the video encoding device.

In the above-mentioned case where the video encoding device implicitlysignals the pixel bit length increase information to the video decodingdevice, there is a problem that PCM encoding cannot be performed due tonon-distortion when the original pixel bit length of the input video islonger than 8 bits. For example, quantization distortion occurs with8-bit pcm_sample_luma[i] and pcm_sample_chroma[i] when the originalpixel bit length of the input video is 10 bits.

To support PCM encoding without quantization distortion when theoriginal pixel bit length of the input video is N bits (N>8),pcm_sample_bit_depth_is_internal_bit_depth_flag which is a flagindicating whether or not the bit length of PCM is the pixel bit lengthafter the pixel bit length increase may be added to the sequenceparameters as shown in FIG. 8.

In the case where pcm_sample_bit_depth_is_internal_bit_depth_flag is 0,the PCM encoder 107 PCM-encodes the input image before the increase ofthe pixel bit length. That is, the PCM encoder 107 PCM-encodes 8-bitpcm_sample_luma[i] and pcm_sample_chroma[i]. The PCM decoder 108PCM-decodes 8-bit pcm_sample_luma[i] and pcm_sample_chroma[i]. The pixelbit length increasing unit 111 shifts PCM-decoded pcm_sample_luma[i] andpcm_sample_chroma[i] to the left respectively byincreased_bit_depth_luma (=internal_bit_depth_luma_minus8) bits andincreased_bit_depth_chroma (=internal_bit_depth_chroma_minus8) bits.

In the case where pcm_sample_bit_depth_is_internal_bit_depth_flag is 1,the PCM encoder 107 PCM-encodes the image increased in pixel bit length.That is, the PCM encoder 107 PCM-encodes pcm_sample_luma[i] of N bits(internal_bit_depth_luma_minus8+8 bits) and pcm_sample_chroma[i] of Nbits (internal_bit_depth_chroma_minus8+8 bits). The PCM decoder 108PCM-decodes pcm_sample_luma[i] of N bits and pcm_sample_chroma[i] of Nbits. The pixel bit length increasing unit 111 shifts PCM-decodedpcm_sample_luma[i] and pcm_sample_chroma[i] to the left by 0 bit (i.e.does not shift PCM-decoded pcm_sample_luma[i] and pcm_sample_chroma[i]to the left).

To support PCM encoding without quantization distortion when theoriginal pixel bit length of the input video is N bits (N>8),pcm_sample_bit_depth_luma_minus8 and pcm_sample_bit_depth_chroma_minus8which are respectively the bit lengths of PCM of luminance and colordifference may be added to the sequence parameters instead ofpcm_sample_bit_depth_is_internal_bit_depth_flag, as shown in FIG. 9.

In the case of adding pcm_sample_bit_depth_luma_minus8 andpcm_sample_bit_depth_chroma_minus8 to the sequence parameters, the PCMencoder 107 PCM-encodes pcm_sample_luma[i] ofpcm_sample_bit_depth_luma_minus8+8 bits and pcm_sample_croma[i] ofpcm_sample_bit_depth_chroma_minus8+8 bits. In the case of addingpcm_sample_bit_depth_luma_minus8 and pcm_sample_bit_depth_chroma_minus8to the sequence parameters, the PCM decoder 108 PCM-decodespcm_sample_luma[i] of pcm_sample_bit_depth_luma_minus8+8 bits andpcm_sample_croma[i] of pcm_sample_bit_depth_chroma_minus8+8 bits. Thepixel bit length increasing unit 111 shifts PCM-decodedpcm_sample_luma[i] and pcm_sample_chroma[i] to the left respectively byincreased_bit_depth_luma bits and increased_bit_depth_chroma bits. Here,increased_bit_depth_luma and increased_bit_depth_chroma are computed asfollows.

increased_bit_depth_luma = internal_bit_depth_luma_minus 8 − pcm_sample_bit_depth_luma_minus 8increased_bit_depth_chroma = internal_bit_depth_chroma_minus 8 − pcm_sample_bit_depth_chroma_minus 8

It is clear from the above-mentioned computation that the video encodingdevice implicitly signals the pixel bit length increase information tothe video decoding device in the case where increased_bit_depth_luma ismore than 0 and also internal_bit_depth_luma_minus8+8 is less than N,and equally the video encoding device implicitly signals the pixel bitlength increase information to the video decoding device in the casewhere internal_bit_depth_chroma_minus8+8 is less than N.

Each of the exemplary embodiments described above may be realized byhardware, or may be realized by a computer program.

An information processing system shown in FIG. 10 includes a processor1001, a program memory 1002, a storage medium 1003 for storing videodata, and a storage medium 1004 for storing a bitstream. The storagemedium 1003 and the storage medium 1004 may be separate storage media,or may be a storage area composed of the same storage medium. As astorage medium, a magnetic storage medium such as a hard disk isapplicable.

In the information processing system shown in FIG. 10, a program forrealizing the functions of the blocks (except the block of the buffer)shown in each of FIGS. 1, 4, and 6 is stored in the program memory 1002.The processor 1001 realizes the functions of the video encoding deviceor the video decoding device shown in FIG. 1, 4, or 6, by executingprocessing according to the program stored in the program memory 1002.

FIG. 11 is a block diagram showing a main part of a video encodingdevice according to the present invention. As shown in FIG. 11, thevideo encoding device according to the present invention includes: pixelbit length increasing means 1 (e.g. the pixel bit length increasing unit101 shown in FIG. 1) for increasing a pixel bit length of an input imagebased on pixel bit length increase information; transform means 2 (e.g.the transformer/quantizer 102 shown in FIG. 1) for transforming outputdata of the pixel bit length increasing means 1; entropy encoding means3 (e.g. the entropy encoder 103 shown in FIG. 1) for entropy-encodingoutput data of the transform means 2; non-compression encoding means 7(e.g. the PCM encoder 107) for non-compression-encoding input data;multiplexed data selection means 8 (e.g. the switch 121) for selectingoutput data of the entropy encoding means 3 or output data of thenon-compression encoding means 7; and multiplexing means 10 (e.g. themultiplexer 110) for multiplexing the pixel bit length increaseinformation in a bitstream, wherein a pixel bit length of an imagecorresponding to the output data of the entropy encoding means 3 and apixel bit length of an image corresponding to the output data of thenon-compression encoding means 7 are different from each other.

To make the pixel bit lengths different from each other, the videoencoding device includes, as an example, means for supplying the inputimage before the increase of the pixel bit length to the non-compressionencoding means 7. In such a case, the input image not increased in pixelbit length is non-compression-encoded (e.g. PCM-encoded).

FIG. 12 is a block diagram showing a main part of another video encodingdevice according to the present invention. As shown in FIG. 12, inaddition to the structure shown in FIG. 11, the other video encodingdevice according to the present invention includes pixel bit lengthdecreasing means 9 (e.g. the pixel bit length decreasing unit 112 shownin FIG. 6) for decreasing a pixel bit length based on the pixel bitlength increase information, wherein the input data of thenon-compression encoding means 7 is output data of the pixel bit lengthdecreasing means 9.

FIG. 13 is a block diagram showing a main part of another video encodingdevice according to the present invention. As shown in FIG. 13, inaddition to the structure shown in FIG. 11, the other video encodingdevice according to the present invention includes: prediction means 10(e.g. the predictor 106 shown in FIG. 1) for predicting an image;inverse transform means 12 (e.g. the inverse transformer/inversequantizer 104 shown in FIG. 1) for inverse-transforming the output dataof the transform means 2; and non-compression decoding means 13 (e.g.the PCM decoder 108 shown in FIG. 1) for decoding the output data of thenon-compression encoding means 7, wherein the non-compression decodingmeans 13 increases a pixel bit length of a decoded image obtained bynon-compression decoding, based on at least the pixel bit lengthincrease information.

FIG. 14 is a block diagram showing a main part of a video decodingdevice according to the present invention. As shown in FIG. 14, thevideo decoding device according to the present invention includes:de-multiplexing means 21 (e.g. the de-multiplexer 201 shown in FIG. 4)for de-multiplexing a bitstream including at least pixel bit lengthincrease information; entropy decoding means 24 (e.g. the entropydecoder 204 shown in FIG. 4) for entropy-decoding transformed data of animage included in the bitstream; inverse transform means 26 (e.g. theinverse transformer/inverse quantizer 206 shown in FIG. 4) forinverse-transforming the entropy-decoded transformed data of the image;non-compression decoding means 23 (e.g. the PCM decoder 203 shown inFIG. 4) for non-compression-decoding non-compression-encoded data of animage included in the bitstream; and decoding control means 22 (e.g. thedecoding controller 202 shown in FIG. 4) for controlling the entropydecoding means 24 and the non-compression decoding means 23, wherein apixel bit length of an image corresponding to input data of the entropydecoding means 24 and a pixel bit length of an image corresponding toinput data of the non-compression decoding means 23 are different fromeach other.

FIG. 15 is a block diagram showing a main part of another video decodingdevice according to the present invention. As shown in FIG. 15, inaddition to the structure shown in FIG. 14, the video decoding deviceaccording to the present invention includes prediction means 27 (e.g.the predictor 207 shown in FIG. 4) for predicting an image.

As described above, the present invention provides means for making apixel bit length of an image corresponding to output data of entropyencoding and a pixel bit length of an image corresponding to output dataof non-compression encoding different from each other, in video encodingbased on pixel bit length increase and non-compression encoding. Thepresent invention can thus solve a problem that output data of PCMencoding increases by the pixel bit length increase amount, while bothenhancing operation precision of intra prediction and inter-frameprediction by pixel bit length extension and guaranteeing a fixedprocessing time for a video encoding device or a video decoding device.

The exemplary embodiments described above may be partly or whollydescribed in the following supplementary notes, though the presentinvention is not limited to the following structures.

(Supplementary Note 1)

A video encoding method including: transforming data obtained byincreasing a pixel bit length of an input image based on pixel bitlength increase information; entropy-encoding the transformed data;non-compression-encoding input data; selecting the entropy-encoded dataor the non-compression-encoded data; and multiplexing the pixel bitlength increase information in a bitstream, wherein a pixel bit lengthof an image corresponding to the entropy-encoded data and a pixel bitlength of an image corresponding to the non-compression-encoded data aredifferent from each other, and wherein the input image before theincrease of the pixel bit length is used as the input data to benon-compression-encoded.

(Supplementary Note 2)

A video encoding method including: transforming data obtained byincreasing a pixel bit length of an input image based on pixel bitlength increase information; entropy-encoding the transformed data;non-compression-encoding input data; selecting the entropy-encoded dataor the non-compression-encoded data; and multiplexing the pixel bitlength increase information in a bitstream, wherein a pixel bit lengthof an image corresponding to the entropy-encoded data and a pixel bitlength of an image corresponding to the non-compression-encoded data aredifferent from each other, wherein the video encoding method includesdecreasing a pixel bit length of data increased in pixel bit length,based on the pixel bit length increase information, and wherein the datadecreased in pixel bit length is used as the input data to benon-compression-encoded.

(Supplementary Note 3)

A video encoding method including: transforming data obtained byincreasing a pixel bit length of an input image based on pixel bitlength increase information; entropy-encoding the transformed data;non-compression-encoding input data; selecting the entropy-encoded dataor the non-compression-encoded data; and multiplexing the pixel bitlength increase information in a bitstream, wherein a pixel bit lengthof an image corresponding to the entropy-encoded data and a pixel bitlength of an image corresponding to the non-compression-encoded data aredifferent from each other, and wherein the video encoding methodincludes: inverse-transforming the transformed data; decoding thenon-compression-encoded data; and, in the decoding, increasing a pixelbit length of a decoded image obtained by non-compression decoding,based on at least the pixel bit length increase information.

(Supplementary Note 4)

A video decoding method including: de-multiplexing a bitstream includingat least pixel bit length increase information; entropy-decodingtransformed data of an image included in the bitstream;inverse-transforming the entropy-decoded transformed data of the image;and non-compression-decoding non-compression-encoded data of an imageincluded in the bitstream, wherein a pixel bit length of an imagecorresponding to the transformed data of the image included in thebitstream and a pixel bit length of an image corresponding to thenon-compression-encoded data of the image included in the bitstream aredifferent from each other, and wherein the video decoding methodincludes, in the non-compression decoding, increasing a pixel bit lengthof a decoded image obtained by the non-compression decoding, based on atleast the pixel bit length increase information.

(Supplementary Note 5)

A video decoding method including: de-multiplexing a bitstream includingat least pixel bit length increase information; entropy-decodingtransformed data of an image included in the bitstream;inverse-transforming the entropy-decoded transformed data of the image;and non-compression-decoding non-compression-encoded data of an imageincluded in the bitstream, wherein a pixel bit length of an imagecorresponding to the transformed data of the image included in thebitstream and a pixel bit length of an image corresponding to thenon-compression-encoded data of the image included in the bitstream aredifferent from each other, and wherein the video decoding methodincludes executing a prediction process of predicting an image.

(Supplementary Note 6)

A video encoding program for causing a computer to execute: a process oftransforming data obtained by increasing a pixel bit length of an inputimage based on pixel bit length increase information; a process ofentropy-encoding the transformed data; a process ofnon-compression-encoding input data; a process of selecting theentropy-encoded data or the non-compression-encoded data; and a processof multiplexing the pixel bit length increase information in abitstream, wherein a pixel bit length of an image corresponding to theentropy-encoded data and a pixel bit length of an image corresponding tothe non-compression-encoded data are different from each other, andwherein the input image before the increase of the pixel bit length isused as the input data to be non-compression-encoded.

(Supplementary Note 7)

A video encoding program for causing a computer to execute: a process oftransforming data obtained by increasing a pixel bit length of an inputimage based on pixel bit length increase information; a process ofentropy-encoding the transformed data; a process ofnon-compression-encoding input data; a process of selecting theentropy-encoded data or the non-compression-encoded data; and a processof multiplexing the pixel bit length increase information in abitstream, wherein a pixel bit length of an image corresponding to theentropy-encoded data and a pixel bit length of an image corresponding tothe non-compression-encoded data are different from each other, whereinthe video encoding program causes the computer to execute a process ofdecreasing a pixel bit length of data increased in pixel bit length,based on the pixel bit length increase information, and wherein the datadecreased in pixel bit length is used as the input data to benon-compression-encoded.

(Supplementary Note 8)

A video encoding program for causing a computer to execute: a process oftransforming data obtained by increasing a pixel bit length of an inputimage based on pixel bit length increase information; a process ofentropy-encoding the transformed data; a process ofnon-compression-encoding input data; a process of selecting theentropy-encoded data or the non-compression-encoded data; and a processof multiplexing the pixel bit length increase information in abitstream, wherein a pixel bit length of an image corresponding to theentropy-encoded data and a pixel bit length of an image corresponding tothe non-compression-encoded data are different from each other, andwherein the video encoding program causes the computer to execute: aprocess of inverse-transforming the transformed data; a process ofdecoding the non-compression-encoded data; and a process of, in thedecoding, increasing a pixel bit length of a decoded image obtained bynon-compression decoding, based on at least the pixel bit lengthincrease information.

(Supplementary Note 9)

A Video Decoding Program for Causing a Computer to execute: a process ofde-multiplexing a bitstream including at least pixel bit length increaseinformation; a process of entropy-decoding transformed data of an imageincluded in the bitstream; a process of inverse-transforming theentropy-decoded transformed data of the image; and a process ofnon-compression-decoding non-compression-encoded data of an imageincluded in the bitstream, wherein a pixel bit length of an imagecorresponding to the transformed data of the image included in thebitstream and a pixel bit length of an image corresponding to thenon-compression-encoded data of the image included in the bitstream aredifferent from each other, and wherein the video decoding program causesthe computer to execute a process of, in the non-compression decoding,increasing a pixel bit length of a decoded image obtained by thenon-compression decoding, based on at least the pixel bit lengthincrease information.

(Supplementary Note 10)

A video decoding program for causing a computer to execute: a process ofde-multiplexing a bitstream including at least pixel bit length increaseinformation; a process of entropy-decoding transformed data of an imageincluded in the bitstream; a process of inverse-transforming theentropy-decoded transformed data of the image; and a process ofnon-compression-decoding non-compression-encoded data of an imageincluded in the bitstream, wherein a pixel bit length of an imagecorresponding to the transformed data of the image included in thebitstream and a pixel bit length of an image corresponding to thenon-compression-encoded data of the image included in the bitstream aredifferent from each other, and wherein the video decoding program causesthe computer to execute a prediction process of predicting an image.

Though the present invention has been described with reference to theabove exemplary embodiments and examples, the present invention is notlimited to the above exemplary embodiments and examples. Various changesunderstandable by those skilled in the art within the scope of thepresent invention can be made to the structures and details of thepresent invention.

This application claims priority based on Japanese Patent ApplicationNo. 2010-159059 filed on Jul. 13, 2010 and Japanese Patent ApplicationNo. 2011-040530 filed on Feb. 25, 2011, the disclosures of which areincorporated herein in their entirety.

REFERENCE SIGNS LIST

-   -   1 pixel bit length increasing means    -   2 transform means    -   3 entropy encoding means    -   7 non-compression encoding means    -   8 multiplexed data selection means    -   9 pixel bit length decreasing means    -   10 multiplexing means    -   11 prediction means    -   12 inverse transform means    -   13 non-compression decoding means    -   21 de-multiplexing means    -   22 decoding control means    -   23 non-compression decoding means    -   24 entropy decoding means    -   26 inverse transform means    -   27 prediction means    -   101 pixel bit length increasing unit    -   102 transformer/quantizer    -   103 entropy encoder    -   104 inverse transformer/inverse quantizer    -   105 buffer    -   106 predictor    -   107 PCM encoder    -   108 PCM decoder    -   109 multiplexed data selector    -   110 multiplexer    -   111 pixel bit length increasing unit    -   112 pixel bit length decreasing unit    -   121 switch    -   122 switch    -   201 de-multiplexer    -   202 decoding controller    -   203 PCM decoder    -   204 entropy decoder    -   205 pixel bit length increasing unit    -   206 inverse transformer/inverse quantizer    -   207 predictor    -   208 buffer    -   209 pixel bit length decreasing unit    -   221 switch    -   222 switch    -   1001 processor    -   1002 program memory    -   1003 storage medium    -   1004 storage medium

The invention claimed is:
 1. A video decoding device comprising: ade-multiplexer configured to de-multiplex a bitstream including at leastinformation indicating a bit length of an image encoded by entropyencoding and information indicating a bit length of an image encoded bynon-compression encoding; an entropy decoder configured toentropy-decode transformed data of an image included in the bitstream;an inverse transformer configured to inverse-transform theentropy-decoded transformed data of the image; a non-compression decoderconfigured to non-compression-decode non-compression-encoded data of animage included in the bitstream; and a decoding controller configured tocontrol the entropy decoder and the non-compression decoder, wherein thenon-compression decoder increases a pixel bit length of the imagecorresponding to the input data of the non-compression decoder, based ondifference between the bit length of the image encoded by entropyencoding and the bit length of the image encoded by non-compressionencoding.
 2. The video decoding device according to claim 1, furthercomprising a predictor configured to predict an image.
 3. A videodecoding method performed by at least one processor, the video decodingmethod comprising: de-multiplexing, by the at least one processor, abitstream including at least information indicating a bit length of animage encoded by entropy encoding and information indicating a bitlength of an image encoded by non-compression encoding;entropy-decoding, by the at least one processor, transformed data of animage included in the bitstream; inverse-transforming, by the at leastone processor, the entropy-decoded transformed data of the image; andnon-compression-decoding, by the at least one processor,non-compression-encoded data of an image included in the bitstream,wherein a pixel bit length of an image corresponding to the input dataof entropy decoding is increased, based on difference between the bitlength of the image encoded by entropy encoding and the bit length ofthe image encoded by the non-compression encoding.
 4. A non-transitorycomputer readable information recording medium storing a video decodingprogram that, when executed by a processor, instructs the processor toperform: de-multiplexing a bitstream including at least informationindicating a bit length of an image encoded by entropy encoding andinformation indicating a bit length of an image encoded bynon-compression encoding; entropy-decoding transformed data of an imageincluded in the bitstream; inverse-transforming the entropy-decodedtransformed data of the image; and non-compression-decodingnon-compression-encoded data of an image included in the bitstream,wherein a pixel bit length of an image corresponding to the input dataof entropy decoding is increased, based on difference between the bitlength of the image encoded by entropy encoding and the bit length ofthe image encoded by the non-compression encoding.